Along with the microminiaturization trend of electronic devices, semiconductor device packages are manufactured to be multifunctional, with increased packaging density and decreased production cost. For instance, a light emitting diode (LED) device has been widely used as a light source to replace a conventional light source, such as an incandescent lamp, due to its micronized size, enhanced energy efficiency, prolonged service life, and shortened response time. However, further improvements in shortening the response time and enhancing the reliability of LED device packages are still being pursued in the field of semiconductor device packaging.
For the purpose of increasing the packaging density and decreasing the packaging size, a conventional semiconductor device package with a quad flat no-lead (QFN) lead frame is provided with solder joints on a bottom surface of the QFN lead frame. However, when the solder joints of the conventional semiconductor device packages are intended for electrically connecting outwardly to external components, quality of the solder joints and completeness of electrical connection between the solder joints and the external components cannot be inspected simply by visual inspection.